As is well known, thinning of glass sheets to be used in flat panel displays (FPD) such as a liquid crystal display, a plasma display, and an OLED display, glass sheets to be used in OLED illumination, glass sheets to be used for manufacturing a tempered glass that is a component of a touch panel, and the like, and glass sheets to be used in panels of solar cells, and the like has been promoted in the current circumstances.
In order to address such current circumstances, in recent years, those glass sheets have been developed so as to be used as glass films having a thickness of 300 μm or less or 200 μm or less. To manufacture this type of glass films, as examples, a down-draw method typified by an overflow down-draw method, a slot down-draw method, and a re-draw method, and a float method have been used.
Those methods involve forming a glass film ribbon by a forming unit through use of a molten glass as a material, drawing the glass film ribbon from the forming unit, and then removing an unnecessary portion of the glass film ribbon by cleaving while conveying the glass film ribbon in a transverse direction by a transverse conveyance unit, to thereby form a glass roll. Specifically, the glass film ribbon is cleaved along a preset cleaving line extending in a longitudinal direction in such a manner that each unnecessary portion including a thick selvage portion both end portions in a width direction of the glass film ribbon that is being conveyed in the transverse direction by the transverse conveyance unit is removed by cleaving with a cleaving unit from the glass film ribbon, and then, one or a plurality of glass film ribbons serving as effective portions are taken up into one or a plurality of glass rolls (see Patent Literature 1 regarding the down-draw method).
Further, in addition to the foregoing, in the case where the glass film ribbon is taken up into a glass roll without removing the unnecessary portion including the selvage portion by cleaving, or in the case where the glass film ribbon is taken up into a glass roll after the unnecessary portion including the selvage portion is removed by cleaving, the glass film ribbon may be conveyed in the transverse direction by the transverse conveyance unit while being taken out from one glass roll and taken up into the other glass roll in a roll-to-roll process.
Also in this type of roll-to-roll process, the glass film ribbon is cleaved along the preset cleaving line extending in the longitudinal direction in such a manner that an unnecessary portion in each of both end portions in the width direction of the glass film ribbon is removed by cleaving with the cleaving unit while the glass film ribbon is being conveyed in the transverse direction by the transverse conveyance unit, and then one or a plurality of glass film ribbons serving as effective portions are taken up into one or a plurality of glass rolls.